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Surviving a fall from 30km

On the 21st of October 2017 the Secunda Amateur Radio Club launched a high altitude balloon, also known as a HAB, from the Radio Control Flying Club at Trichardt, South Africa.

Eleven teams were gathered on that day to build and deploy payloads on the balloon - electronic instruments designed to gather and store environmental data and beam it back from the edges of the atmosphere. Teams came from all walks - SANSA (South Aftican National Space Agency), the South African Radio League, local high schools. And some commercial providers, including XinaBox.

The balloon used was made from natural latex and filled with Helium. The total payload (weight of the instruments it carried) was 9kg. It soared to a height of 29.5km, roughly 100,000 feet, and reached a maximum horizontal speed of 182km/h.

The XinaBox team constructed 3 separate instruments for the journey, and these were built the morning of the launch. One used a RPi Zero with camera and a servo arm to capture some stunning images of the atmosphere:

In this sort of experiment the balloons do pop - that was no surprise and an on-board parachute is used to bring the payloads down to Earth. In this instance there were issues with the parachute - it deployed but did not work as it should. A witness described it as being more of a blanket than a parachute. The payloads plunged back to Earth and hit the surface at 9m/s - roughly 70km/h.

Payloads after hitting the ground at 70km/h

Recovering the payloads is part of the fun of this sort of activity, and these came down near Ermelo, about 80km away, very close to where they were predicted to land. The teams then recovered their kit and extracted whatever data might have been recorded.

And that is usually the end of it - a fantastic day out, loads of fun and some great educational opportunities for all involved, especially the school children.

But there is an unexpected twist in the tail: imagine taking any kind of electronic device and smashing it into the ground at 70km/h... that's equivalent to throwing an iPad out the window when driving fast on a motorway and can be compared to beating the device with a hammer. No one expected their instruments to still work after the fall - descending from 30km with a blanket for a parachute usually does not end well for anything, especially electronics.

The XinaBox kit worked perfectly after the impact, and was the only kit to do so. The non-rigid nature of the connectivity gives redundancy and mechanical strength and, as this inadvertent experiment showed, allows for the force of heavy impacts to be absorbed and dissipated. All 3 of the XinaBox instruments survived intact - we were able to verify that the xChips could still communicate with each other and perform their functions.

Our thanks to Brendan and Ben who represented XinaBox. Thanks also to the Secunda Amatuer Radio club for putting on this amazing annual event and to all the other participants who helped make it a memorable day.

The XinaBox team inspecting the fallen payloads - little expecting the kit would still work!